Improvement in exhaust-valve gears



a. H. conuss EXHAUST VALVE GEAR.

No.177,099. Patented May 9,1876.

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' NITED GEORGE H. GORLISS, OF PROVIDENGE, RHODE ISLAND.

' IMPROVEMENT IN EXHAUST-VALVE GEARS.

Specification forming part of Letters Patent No. 1 77,099, dated May 9, 1876; application filed January 10, 1876;

of Providence, in the State of Rhode Island, have invented certain Improvements relating to Exhaust-Valve Gear for Steam-Engines, of

which the following is a specification:

- I use the word valve-gear in the sense in which it is generally used by engineering writers to mean the mechanism of rods, links, rock-shafts, &c.,'which contribute to impart motion, or to control the motion of valves. My invention is intended more particularly for use with the valves sliding on cylindrical seats, but it may be adapted to other styles of valves.

I will describe it as applied to valves which are operated. by being turned a quarter revolution, more or less. Such valve (not represented) when standing in one position forms a free communication through which the exhaust steam may be discharged from .the'

cylinder into the condenser or into the atmosphere. When turned to the other extreme position ittightly closes the corresponding exhaust-port. I

It is necessary that for about half the time the exhaust-port shall be either partially or entirely open.- When the port is partially open the steam is liable to be wire-drawn through such partial opening; therefore it is desirable that the opening and closing movement shall be effected as rapidly as prac: ticable.

In the construction of large classes of steam-engines this fact is appreciated, and the valves are opened and closed by cams in order to effect the motion suddenly. In view of the advantages in the employmentof smoothly-working eccentrics rather than cams, I have devised means whereby I can realize a close approximation to the sudden cam movement while deriving the motion from eccentrics.

The following is a description of what I consider the best means of carrying out my invention as applied to an engine inwhich the exhaust-valves are operated by oscillating-shafts which extend out through stuffiugboxes in the side of the exhaust-chests.

The accompanying drawings form a part of this specification.

Figures 1 and 2 are side elevations, each showing the same portion of the cylinder and exhaust-valve chests of a horizontal engine. Fig. 3 is a diagram showing the peculiarities.

Similar letters of reference indicate corresponding parts in all the figures.

There are two exhaust-valves (not represented) lying at or near the level of the lower side of the cylinder A. Each is equipped with a stem, B, having a rigid lateral arm, B. The valve is controlled by acting upon the extremity of this arm by means. of a suitable link. a

I mount near the sweep of that arm a rocking lever, and I link the end of the valve-arm to one arm thereof by a link, 0. Now, a vibratory motion given to my said lever by any means-as, for example,- by means of a direct connection with an eccentricwill give to the valve a quicker movement near the middle and a slower near each end of each movement, by virtue of the positions assumed .by. the link 0 and the different relations which the arms and their motions sustain to each other at difi'erent periods. Near the middle of each movementof the .exhaustfvalve, while the valve-portis opening or closing, the connecting-link 0 works at a very acute angle to the arm B on the valve-shaft B, while toward both extremes of its movement it works nearly at right angles thereto. In the position where the valve is only partially open, a little movement of the eccentric induces a great movement of the valve. But at and near each end of the motion the link stands nearly at right angles to the valve-arm or valve-lever B,and oblique to the arm D of the rocker-lever D. In that position a given amount of motion of the eccentric induces a very much smaller movement of the valve.

In practice I employa further rocking part, M, which communicates the motion to both valves.

The arrangement is very fully shown in the figures.

The dottedarcs in Fig. 2 indicate the extent of the travel.

E is a rod or link connected to the respective arm D and communicating motion thereto from the pin 0, carried on the rocking-wheel M, which latter receives the ordinary oscilthe links or rods E are reciprccated; The

motion is the familiar one, slow near each end of the movement and considerably faster in the middle part of its movement in both directions. But in order to open and-close the valves quickly it is desirable that the movement of the valves shall have these qualities in a much higher degree.

The links' E by their reciprocation commnnicate a corresponding moderate oscillating ino'tion to'each lever D 1), and each ant D f has a corresponding motion to an extent iiidicated by thedo'tted linesti'uck from the cen ter d, and passing near the stem Bof the "cor- -to its fullest extent in one directio'inall the parts are in the position to vvhichthey iare approaching in Fig; i When the valve is at inidthrow, all the parts are in the position shown in Fig: 2. In this inidthrowposition the link 0 stands at about right an les to the 1 moderately-Oscillating.arm 1J from ii'lii-ch it receives motion, but stands quite obliquely to the arm B, to which it is communicating motion; By reason of its position it has tlie efl'ectto induce a, more rapid motihnof the? At each; end of its throw, the relation of the arihs to each other, and of the link to both, has he'- 1 coins so changed that a great amount of mo-;

arm B' at the middle of its throiv:

tion of the arin Dis' required to induce a 53 small motion of the arm 13; I

Theresultingmotion of the mvetssbest aireadyexplained. The valve "changes from 1 its closed to its open positionalmostinstaiitly, j and it "again changes as rapidly to the'clos'ed;

DOSitidn;

Various modifications may be mane in seals of the details. Thus, for example, the tas in'g shaft OI Wheel M may be dispensed "with;

and the rods E may be connected directly to eccentrics on the shaft, thel'evers 19 -1) being bent or straightened to correspond with any change of inclination of the rods E. The effect may be heightened by lengthening the arms B .D and the link 0, while the position of the shaft B and the stud remains the same.

This modification, by bringing the arc'of motion of the arm 13 nearer to thecenter of the aids of'the valve, increases the obliquity of the position at midthrow, and thus induces a moremarked effect, ,If ,desired a, in any-case, 'th" efl'ect may be sun farmer inereasea by employing two, or even, it is theoretically possible to use, three or a larger number of levers analogous to D D an d of links analogous to (3, playing sacrament r.

ia a i It t H M Ta man-sa ot' the e i 'a arts near the middle of each ovenjient is mm d haeeusp ce; and

responding "alve; VV-he'n the valve is turned; the ri 'lathe 11 part near theeiid of each move p t isfi ted ythe areas outside 'o'f the sta ea silicate: warns "the am: at sssnona a re nant incubus for steam ng inesq y i 1; In tt ihin; 1i with t snacnsnuarm ism;iasstsua vawe arc ass-r the shaft Bfliiil the ash: U connecting the arms B and D all combined and arrangeu for joint operation, as an the purposes herein s ecifies, v 1

v 2; The lasers 3) 19 the respective i "1 With tlieiohking-pl mm sum rim-titans l s was specified:

, ni ssnmtiiy wnersor I have hermit set my hand this 6th any hfOtdbfilS'iS, in the presence of two subscribing wi nesses;

p I GEO. H; OURIJISS: Witne sesg N a i 1 en e rem- 1, En. W.RA'YN$FOR1.

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